Yucca Trees

Last summer my outdoor yucca tree grew a long wooden like pole from the middle and there were lots of flowers attached to the pole. This year it died but there are about 12 young yucca shoots growing and I don't know how to separate them from the wood like root that they are attached to. They all seem to have their own wood root growing from the original plant. The new shoots are getting quite big, so do I leave them to all grow together? I haven't got a clue as to what I do with them. Help, please.